Microfluidic delivery system

ABSTRACT

Microfluidic delivery systems for dispensing a fluid composition into the air comprising microfluidic die and at least one heating element that is configured to receive an electrical signal comprising a certain on-time and wave form to deliver a fluid composition into the air.

FIELD OF THE INVENTION

The present invention relates to a microfluidic delivery systemcomprising a microfluidic delivery member and methods for delivering afluid composition into the air.

BACKGROUND OF THE INVENTION

Various systems exist to deliver fluid compositions, such as perfumemixtures, into the air by an energized (i.e. electrically/batterypowered) atomization system. Such systems include battery-poweredautomatic aerosol air fresheners, sold under the tradename AirWick® byReckitt Benckiser. Another attempt is a piezoelectric actuator thatatomizes a volatile composition into fluid droplets in the air, soldunder the tradename Glade® by S.C. Johnson & Son.

Recent attempts have been made to deliver fluid compositions, includingscented inks, by means of an ink jet spray head. These attempts aredirected to emitting a fluid composition onto an adjacentsubstrate/surface or emitting a fluid composition into an adjacentspace. For example, JP2007054445A1 describes an ink jet head that spraysfluids into a personal space (e.g. near a user's nose) for attaining abenefit. JP2005125225 describes an ink jet head that sprays aninsecticide towards a target surface.

There remains a need for an improved microfluidic delivery system toefficiently deliver sufficient quantities of a fluid composition intothe air to deliver a benefit, e.g., freshen a room or living space, withminimal deposition of the fluid composition onto adjacent surfaces.

SUMMARY OF THE INVENTION

In one embodiment, there is provided a delivery system comprising amicrofluidic delivery system comprising: a microfluidic die comprising aplurality of nozzles for dispensing a fluid composition and comprisingat least one heating element configured to receive an electrical firingpulse, wherein said electrical firing pulse is delivered during a firingperiod (t_(ON)) from about 0.25 seconds to about 10 seconds, andwherein, during said firing period, said electrical filing pulse ispulsed at about 100 Hertz to about 6000 Hertz with a fire time(t_(FIRE)) from about 1 microsecond to about 3 microseconds.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic isometric view of a microfluidic delivery systemin accordance with one embodiment.

FIG. 2A is a schematic isometric views of a microfluidic deliverycartridge and a holder in accordance with one embodiment.

FIG. 2B is an exploded view of the structure in FIG. 2A.

FIG. 3. is a cross-section schematic view of line 3-3 in FIG. 2A.

FIG. 4 is a cross-section schematic view of line 4-4 in FIG. 2B.

FIGS. 5A-5B are schematic isometric views of a microfluidic deliverymember in accordance with an embodiment.

FIG. 5C is an exploded view of the structure in FIG. 5A.

FIGS. 6A-6C are schematic isometric views of a microfluidic die atvarious layers in accordance with another embodiment.

FIG. 7A is a cross-section schematic view of line 7-7 in FIG. 6.

FIG. 7B is an enlarged view of a portion of FIG. 7A.

FIG. 8A is a cross-section view of line 8A-8A in FIG. 6A.

FIG. 8B is a cross-section view of line 8B-8B in FIG. 6A.

FIG. 9 is a cross-section schematic view of a fluid path of amicrofluidic cartridge in accordance with one embodiment of the presentinvention.

FIG. 10 is a diagram of wave forms and pulse timings of electricalsignals in accordance with on embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

The present invention provides a microfluidic delivery system 10comprising a microfluidic delivery member 64 and methods for deliveringfluid compositions into the air.

The delivery system 10 of the present invention may comprise a housing12 and cartridge 26. The cartridge 26 may comprise a reservoir 50 forcontaining a volatile composition, and a microfluidic delivery member64. The housing 12 may comprise a microprocessor and an outlet 20.

While the below description describes the delivery system 10 comprisinga housing 12 and a cartridge 26, both having various components, it isto be understood that the delivery system 10 is not limited to theconstruction and arrangement set forth in the following description orillustrated in the drawings. The invention is applicable to otherembodiments or may be practiced or carried out in various ways. Forexample, the components of the housing 12 may be located on thecartridge 26 and vice-versa. Further, the housing 12 and cartridge 26may be configured as a single unit versus constructing a cartridge thatis separable from the housing as described in the following description.

Housing

The microfluidic delivery system 10 may include a housing 12 constructedfrom a single piece or having multiple surfaces that are assembled toform the housing. The housing 12 may have an upper surface 14, a lowersurface 16, and a body portion 18 between the upper and lower surfaces.The upper surface of the housing 12 includes an outlet 20 that places anenvironment external to the housing in fluid communication with aninterior portion 22 of the housing 12. The interior portion 22 of thehousing 12 may includes a holder member 24 that holds a microfluidiccartridge 26, which may be removable. As will be explained below, themicrofluidic delivery system 10 may be configured to use thermal energyto deliver fluid from within the microfluidic fill cartridge 26 to anenvironment external to the housing 12.

Access to the interior portion 22 of the housing 12 is provided by anopening 28 in the housing. The opening 28 is accessible by a cover ordoor 30 of the housing 12. In the illustrated embodiment, the door 30rotates to provide access to the opening 28.

The holder member 24 includes an upper surface 32 and a lower surface 34that are coupled together by one or more sidewalls 36 and has an openside 38 through which the microfluidic cartridge 26 can slide in andout. The upper surface 32 of the holder member 24 includes an opening 40that is aligned with the first hole 20 of the housing 12. The holdermember 24 holds the microfluidic cartridge 26 in position.

The housing 12 may include external electrical connection elements forcoupling with an external power source. The external electricalconnection elements may be a plug configured to be plugged into anelectrical outlet or battery terminals. Internal electrical connectionscouple the external electrical connection elements to the holder member24 to provide power to the microfluidic cartridge 26. The housing 12 mayinclude a power switch 42 on a front of the housing.

FIG. 2A shows the microfluidic cartridge 26 in the holder member 24without the housing 12, and FIG. 2B shows the microfluidic cartridge 26removed from the holder member 24. A circuit board 44 is coupled to theholder member by a screw 46. As will be explained in more detail below,the circuit board 44 includes electrical contacts 48 that electricallycouple to the microfluidic cartridge 26. The electrical contacts 48 ofthe circuit board 44 are in electrical communication with the internaland external electrical connection elements.

Cartridge

Reservoir

The microfluidic delivery system 10 includes a microfluidic cartridge 26which includes a reservoir 50 for containing a fluid composition. Insome embodiments, the reservoir 50 is configured to contain from about 5to about 50 ml, alternatively from about 10 to about 30 ml,alternatively from about 15 to about 20 ml of fluid composition. Thedelivery system may be configured to have multiple reservoirs, eachcontaining the same or a different composition. The reservoir 50 may beformed as a separate construction, so as to be replaceable (e.g. arefill cartridge). The reservoir can be made of any suitable materialfor containing a fluid composition including glass and plastic.

A lid 54, having an inner surface 56 and an outer surface 58, is securedto an upper portion 60 of the reservoir to cover the reservoir 50. Thelid 54 may be secured to the reservoir 50 via a variety of ways known inthe art. Between the lid 54 and the reservoir 50, there may be an o-ring62 for forming a seal therebetween to prevent fluid from leaking out ofthe reservoir.

A microfluidic delivery member 64 is secured to an upper surface 66 ofthe lid 54 of the microfluidic cartridge 26. The microfluidic deliverymember 64 includes an upper surface 68 and a lower surface 70 (see FIGS.5A-5C). A first end 72 of the upper surface 68 includes electricalcontacts 74 for coupling with the electrical contacts 48 of the circuitboard 44 when placed in the holder member 24. As will be explained inmore detail below, a second end 76 of the microfluidic delivery member64 includes a part of a fluid path that passes through an opening 78 fordelivering fluid.

Fluid Transport Member

FIG. 3 is a cross-section view of the microfluidic cartridge 26 in theholder member 24 along line 3-3 shown in FIG. 2A. Inside the reservoir50 is a fluid transport member 80 that has a first end 82 in the fluid52 in the reservoir 50 and a second end 84 that is above the fluid. Thesecond end 84 of the fluid transport member 80 is located below themicrofluidic delivery member 64. The fluid transport member 80 deliversfluid from the reservoir 50 to the microfluidic delivery member 64.Fluid can travel by wicking, diffusion, suction, siphon, vacuum, orother mechanism. In some embodiments, the fluid may be transported tothe microfluidic delivery member by a gravity fed system known in theart.

In some embodiments, the microfluidic delivery system 10 may include afluid channel positioned in a flow path between the fluid transportmember 80 and the reservoir 50 or between the fluid transport member 80and the microfluidic delivery member 64. A channel may be useful inconfigurations where the reservoir, transport member or the microfluidicdelivery member are not perfectly aligned vertically wherein thecapillary fluid channel is used to still enable capillary flow ofliquid.

The fluid transport member 80 may be any commercially availablecapillary tube or wicking material, such as a metal or fabric mesh,sponge, or fibrous or porous wick that contains multiple interconnectedopen cells which form capillary passages to draw a fluid composition upfrom the reservoir to come in contact with the fluid feed of themicrofluidic delivery member. Non-limiting examples of suitablecompositions for the fluid transport member include polyethylene,ultra-high molecular weight polyethelene, nylon 6, polypropylene,polyester fibers, ethyl vinyl acetate, polyether sulfone, polyvinylidenefluoride, and polyethersulfone, polytetrafluroethylene, and combinationsthereof. In some embodiments, the fluid transport member 80 is free of apolyurethane foam. Many traditional ink jet cartridges use an open-cellpolyurethane foam which can be incompatible with perfume mixtures overtime (e.g. after 2 or 3 months) and can break down.

In some embodiments, the fluid transport member 80 may be a high densitywick composition to aid in containing the scent of a perfume mixture. Inone embodiment, the fluid transport member is made from a plasticmaterial chosen from high-density polyethylene or polyester fiber. Asused herein, high density wick compositions include any conventionalwick material known in the art having a pore radius or equivalent poreradius (e.g. in the case of fiber based wicks) ranging from about 20microns to about 200 microns, alternatively from about 30 microns toabout 150 microns, alternatively from about 30 microns to about 125microns, alternatively, about 40 microns to about 100 microns.

Regardless of the material of manufacture, where a wicking material isused, the fluid transport member 80 can exhibit an average pore sizefrom about 10 microns to about 500 microns, alternatively from about 50microns to about 150 microns, alternatively about 70 microns. Theaverage pore volume of the wick, expressed as a fraction of the fluidtransport member not occupied by the structural composition, is fromabout 15% to about 85%, alternatively from about 25% to about 50%. Goodresults have been obtained with wicks having an average pore volume ofabout 38%.

The fluid transport member 80 may be any shape that is able to deliverfluid from the reservoir 50 to the microfluidic delivery member 64.Although the fluid transport member 80 of the illustrated embodiment hasa width dimension, such as diameter, that is significantly smaller thanthe reservoir 50, it is to be appreciated that the diameter of the fluidtransport member 80 may be larger and in one embodiment substantiallyfills the reservoir 50. The fluid transport member 80 can also be ofvariable length, such as, from about 1 mm to about 100 mm, or from about5 mm to about 75 mm, or from about 10 mm to about 50 mm.

As best shown in FIG. 4, the second end 84 of the fluid transport member80 is surrounded by a transport cover 86 that extends from the innersurface of the lid 54. The second end 84 of the fluid transport member80 and the transport cover 86 form a chamber 88. The chamber 88 may besubstantially sealed between the transport cover 86 and the fluidtransport member 80 to prevent air from the reservoir 50 from enteringthe chamber.

Microfluidic Delivery Member

The delivery system 10 of the present invention employs a microfluidicdelivery member 64. Microfluidic delivery member 64 of the presentinvention may employ aspects of ink-jet print head systems.

In a typical “drop-on-demand” ink-jet printing process, a fluid isejected through a very small orifice of a diameter typically about0.0024 inches (5-50 microns) in the form of minute droplets by rapidpressure impulses. The rapid pressure impulses are typically generatedin the print head by either expansion of a piezoelectric crystalvibrating at a high frequency or volatilization of a volatilecomposition (e.g. solvent, water, propellant) within the ink by rapidheating cycles. Thermal ink-jet printers employ a heating element withinthe print head to volatilize a portion of the composition that propels asecond portion of fluid through the orifice nozzle to form droplets inproportion to the number of on/off cycles for the heating element. Thefluid is forced out of the nozzle when needed. Conventional ink-jetprinters are more particularly described in U.S. Pat. Nos. 3,465,350 and3,465,351.

The microfluidic delivery member 64 of the present invention may employaspects of any known ink-jet print head system or, more particularly,aspects of thermal ink-jet print heads. The microfluidic delivery member64 of the present invention may be in electrical communication with apower source and may include a printed circuit board (“PCB”) 106 and amicrofluidic die 92 that is in fluid communication with the fluidtransport member 80.

As shown in FIGS. 4 and 5A-5C, the microfluidic delivery member 64 mayinclude a printed circuit board 106 (“PCB”). The board 106 is a rigidplanar circuit board, having the upper and lower surfaces 68, 70. Themicrofluidic delivery member 64 may comprise a planar surface area ofless than about 25 mm², or about 6 mm².

The board 106 includes first and second circular openings 136, 138 andan oval opening 140. Prongs 142 from the lid 54 extend through theopenings 136, 138, 140 to ensure the board 106 is aligned with the fluidpath appropriately. The oval opening 140 interacts with a wider prong sothat the board 106 can only fit onto the lid 54 in one arrangement.Additionally, the oval openings allow for PCB and lid tolerances.

The board 106 is of a conventional construction. It may comprise afiberglass-epoxy composite substrate material and layers of conductivemetal, normally copper, on the top and bottom surfaces. The conductivelayers are arranged into conductive paths through an etching process.The conductive paths are protected from mechanical damage and otherenvironmental effects in most areas of the board by a photo-curablepolymer layer, often referred to as a soldermask layer. In selectedareas, such as the liquid flow paths and wire bond attachment pads, theconductive copper paths are protected by an inert metal layer such asgold. Other material choices could be tin, silver, or other lowreactivity, high conductivity metals.

Still referring to FIGS. 5A-5C, the board 106 may include all electricalconnections—the contacts 74, the traces 75, and the contact pads 112—onthe upper surface 68 of the board 106. For example, a top surface 144 ofthe electrical contacts 74 that couple to the housing are parallel to anx-y plane. The upper surface 68 of the board 106 is also parallel to thex-y plane. In addition, a top surface of the nozzle plate 132 of the die92 is also parallel to the x-y plane. The contact pads 112 also have atop surface that is parallel to the x-y plane. By forming each of thesefeatures to be in parallel planes, the complexity of the board 106 maybe reduced and is easier to manufacture. In addition, this allowsnozzles 130 to eject the fluid vertically (directly up or at an angle)away from the housing 12, such as could be used for spraying scentedoils into a room as air freshener. This arrangement could create a plumeof fine droplets about 5 cm to about 10 cm upward away from the nozzles130 and housing 12.

The board 106 includes the electrical contacts at the first end andcontact pads 112 at the second end proximate the die 92. Electricaltraces from the contact pads 112 to the electrical contacts are formedon the board and may be covered by the solder mask or anotherdielectric. Electrical connections from the die 92 to the board 106 maybe established by a wire bonding process, where small wires, which maybe composed of gold or aluminum, are thermally attached to bond pads onthe silicon die and to corresponding bond pads on the board. Anencapsulant material, normally an epoxy compound, is applied to the wirebond area to protect the delicate connections from mechanical damage andother environmental effects.

On the lower surface of the board 106, a filter 96 separates the opening78 of the board from the chamber 88 at the lower surface of the board.The filter 96 is configured to prevent at least some of particulatesfrom passing through the opening 78 to prevent clogging the nozzles 130of the die 92. In some embodiments, the filter 96 is configured to blockparticulates that are greater than one third of the diameter of thenozzles 130. It is to be appreciated that, in some embodiments, thefluid transport member 80 can act as a suitable filter 96, so that aseparate filter is not needed. In one embodiment, the filter 96 is astainless steel mesh. In other embodiments, the filter 96 is randomlyweaved mesh, polypropylene or silicon based.

The filter 96 may be attached to the bottom surface with an adhesivematerial that is not readily degraded by the fluid in the reservoir 50.In some embodiments, the adhesive may be thermally or ultravioletactivated. The filter 96 is positioned between the chamber 88 and thedie 92. The filter 96 is separated from the bottom surface of themicrofluidic delivery member 64 by a mechanical spacer 98. Themechanical spacer 98 creates a gap 99 between the bottom surface 70 ofthe microfluidic delivery member 64 and the filter 96 proximate thethrough hole 78. The mechanical spacer 98 may be a rigid support or anadhesive that conforms to a shape between the filter 96 and themicrofluidic delivery member 64. In that regard, the outlet of thefilter 96 is greater than the diameter of the second through hole 78 andis offset therefrom so that a greater surface area of the filter 96 canfilter fluid than would be provided if the filter was attached directlyto the bottom surface 70 of the microfluidic delivery member 64 withoutthe mechanical spacer 98. It is to be appreciated that the mechanicalspacer 98 allows suitable flow rates through the filter 96. That is, asthe filter 96 accumulates particles, the filter will not slow down thefluid flowing therethrough. In one embodiment, the outlet of the filter96 is about 4 mm² or larger and the standoff is about 700 microns thick.

The opening 78 may be formed as an oval, as is illustrated in FIG. 5C;however, other shapes are contemplated depending on the application. Theoval may have the dimensions of a first diameter of about 1.5 mm and asecond diameter of about 700 microns. The opening 78 exposes sidewalls102 of the board 106. If the board 106 is an FR4 PCB, the bundles offibers would be exposed by the opening. These sidewalls are susceptibleto fluid and thus a liner 100 is included to cover and protect thesesidewalls. If fluid enters the sidewalls, the board 106 could begin todeteriorate, cutting short the life span of this product.

The board 106 carries a microfluidic die 92. The die 92 comprises afluid injection system made by using a semiconductor micro fabricationprocess such as thin-film deposition, passivation, etching, spinning,sputtering, masking, epitaxy growth, wafer/wafer bonding, microthin-film lamination, curing, dicing, etc. These processes are known inthe art to make MEMs devices. The die 92 may be made from silicon,glass, or a mixture thereof. The die 92 comprises a plurality ofmicrofluidic chambers 128, each comprising a corresponding actuationelement: heating element or electromechanical actuator. In this way, thedie's fluid injection system may be micro thermal nucleation (e.g.heating element) or micro mechanical actuation (e.g. thin-filmpiezoelectric). One type of die for the microfluidic delivery member ofthe present invention is an integrated membrane of nozzles obtained viaMEMs technology as described in U.S. 2010/0154790, assigned toSTMicroelectronics S.R.I., Geneva, Switzerland. In the case of athin-film piezo, the piezoelectric material (e.g. lead zirconinumtitanate)” is typically applied via spinning and/or sputteringprocesses. The semiconductor micro fabrication process allows one tosimultaneously make one or thousands of MEMS devices in one batchprocess (a batch process comprises of multiple mask layers).

The die 92 is secured to the upper surface of the board 106 above theopening 78. The die 92 is secured to the upper surface of the board 106by any adhesive material configured to hold the semiconductor die to theboard. The adhesive material may be the same or different from theadhesive material used to secure the filter 96 to the microfluidicdelivery member 64.

The die 92 may comprise a silicon substrate, conductive layers, andpolymer layers. The silicon substrate forms the supporting structure forthe other layers, and contains a channel for delivering fluid from thebottom of the die to the upper layers. The conductive layers aredeposited on the silicon substrate, forming electrical traces with highconductivity and heaters with lower conductivity. The polymer layersform passages, firing chambers, and nozzles 130 which define the dropformation geometry.

FIGS. 6A-6C include more details of the microfluidic die 92. Themicrofluidic die 92 includes a substrate 107, a plurality ofintermediate layers 109, and a nozzle plate 132. The plurality ofintermediate layers 109 include dielectric layers and a chamber layer148 that are positioned between the substrate and the nozzle plate 132.In one embodiment, the nozzle plate 132 is about 12 microns thick.

The die 92 includes a plurality of electrical connection leads 110 thatextend from one of the intermediate layers 109 down to the contact pads112 on the circuit board 106. At least one lead couples to a singlecontact pad 112. Openings 150 on the left and right side of the die 92provide access to the intermediate layers 109 to which the leads 110 arecoupled. The openings 150 pass through the nozzle plate 132 and chamberlayer 148 to expose contact pads 152 that are formed on the intermediatedielectric layers. In other embodiments that will be described below,there may be one opening 150 positioned on only one side of the die 92such that all of the leads that extend from the die extend from one sidewhile other side remains unencumbered by the leads.

The nozzle plate 132 may include about 4 to about 64 nozzles 130, orabout 6 to about 48 nozzles, or about 8 to about 32 nozzles, or about 8to about 24 nozzles, or about 12 to about 20 nozzles. In the illustratedembodiment, there are eighteen nozzles 130 through the nozzle plate 132,nine nozzles on each side of a center line. Each nozzle 130 may deliverabout 1 to about 10 picoliters, or about 2 to about 8 picoliters, orabout 4 to about 6 picoliters of a fluid composition per electricalfiring pulse. The nozzles 130 may be positioned about 60 um to about 110μm apart. In one embodiment, twenty nozzles 130 are present in a 3 mm²area. The nozzles 130 may have a diameter of about 5 μm to about 40 μm,or 10 μm to about 30 μm, or about 20 μm to about 30 μm, or about 13 μmto about 25 μm. FIG. 6B is a top down isometric view of the die 92 withthe nozzle plate 132 removed, such that the chamber layer 148 isexposed.

Generally, the nozzles 130 are positioned along a fluidic feed channelthrough the die 92 as shown in FIGS. 7A and 7B. The nozzles 130 mayinclude tapered sidewalls such that an upper opening is smaller than alower opening. In this embodiment, the heater is square, having sideswith a length. In one example, the upper diameter is about 13 μm toabout 18 μm and the lower diameter is about 15 μm to about 20 μm. At 13μm for the upper diameter and 18 μm for the lower diameter, this wouldprovide an upper area of 132.67 μm and a lower area of 176.63 μm. Theratio of the lower diameter to the upper diameter would be around 1.3to 1. In addition, the area of the heater to an area of the upperopening would be high, such as greater than 5 to 1 or greater than 14 to1.

Each nozzle 130 is in fluid communication with the fluid in thereservoir 50 by a fluid path. Referring to FIG. 4 and FIGS. 7A and 7B,the fluid path from the reservoir 50 includes the first end 82 of thefluid transport member 80, through the transport member to the secondend 84 of the transport member, through the chamber 88, through thefirst through-hole 90, through the opening 78 of the board 106, throughan inlet 94 of the die 92, then through a channel 126, and then throughthe chamber 128, and out of the nozzle 130 of the die.

Proximate each nozzle chamber 128 is a heating element 134 (see FIGS. 6Cand 8A) that is electrically coupled to and activated by an electricalsignal being provided by one of the contact pads 152 of the die 92.Referring to FIG. 6C, each heating element 134 is coupled to a firstcontact 154 and a second contact 156. The first contact 154 is coupledto a respective one of the contact pads 152 on the die by a conductivetrace 155. The second contact 156 is coupled to a ground line 158 thatis shared with each of the second contacts 156 on one side of the die.In one embodiment, there is only a single ground line that is shared bycontacts on both sides of the die. Although FIG. 6C is illustrated asthough all of the features are on a single layer, they may be formed onseveral stacked layers of dielectric and conductive material. Further,while the illustrated embodiment shows a heating element 134 as theactivation element, the die 92 may comprise piezoelectric actuators ineach chamber 128 to dispense the fluid composition from the die.

In use, when the fluid in each of the chambers 128 is heated by theheating element 134, the fluid vaporizes to create a bubble. Theexpansion that creates the bubble causes fluid to eject from the nozzle130 and to form a plume of one or more droplets.

FIG. 7A is a cross-section view through the die of FIG. 6, through cutlines 7-7. FIG. 7B is an enhanced view of the cross-section in FIG. 7A.The substrate 107 includes an inlet path 94 coupled to a channel 126that is in fluid communication with individual chambers 128, formingpart of the fluid path. Above the chambers 128 is the nozzle plate 132that includes the plurality of nozzles 130. Each nozzle 130 is above arespective one of the chambers 128. The die 92 may have any number ofchambers and nozzles, including one chamber and nozzle. In theillustrated embodiment, the die includes eighteen chambers eachassociated with a respective nozzle. Alternatively, it can have tennozzles and two chambers provided fluid for a group of five nozzles. Itis not necessary to have a one-to-one correspondence between thechambers and nozzles.

As best seen in FIG. 7B, the chamber layer 148 defines angled funnelpaths 160 that feed the fluid from the channel 126 into the chamber 128.The chamber layer 148 is positioned on top of the intermediate layers109. The chamber layer defines the boundaries of the channels and theplurality of chambers 128 associated with each nozzle 130. In oneembodiment, the chamber layer is formed separately in a mold and thenattached to the substrate. In other embodiments, the chamber layer isformed by depositing, masking, and etching layers on top of thesubstrate.

The intermediate layers 109 include a first dielectric layer 162 and asecond dielectric layer 164. The first and second dielectric layers arebetween the nozzle plate and the substrate. The first dielectric layer162 covers the plurality of first and second contacts 154, 156 formed onthe substrate and covers the heaters 134 associated with each chamber.The second dielectric layer 164 covers the conductive traces 155.

FIG. 8A is a cross-section view through the die 92 along the cut line8A-8A in FIG. 6A. The first and second contacts 154, 156 are formed onthe substrate 107. The heaters 134 are formed to overlap with the firstand second contacts 154, 156 of a respective heater assembly. Thecontacts 154, 156 may be formed of a first metal layer or otherconductive material. The heaters 134 may be formed of a second metallayer or other conductive material. The heaters 134 are thin-filmresistors that laterally connect the first and second contacts 154, 156.In other embodiments, instead of being formed directly on a top surfaceof the contacts, the heaters 134 may be coupled to the contacts 154, 156through vias or may be formed below the contacts.

In one embodiment, the heater 134 is a 20-nanometer thick tantalumaluminum layer. In another embodiment, the heater 134 may includechromium silicon films, each having different percentages of chromiumand silicon and each being 10 nanometers thick. Other materials for theheaters 134 may include tantalum silicon nitride and tungsten siliconnitride. The heaters 134 may also include a 30-nanometer cap of siliconnitride. In an alternative embodiment, the heaters 134 may be formed bydepositing multiple thin-film layers in succession. A stack of thin-filmlayers combine the elementary properties of the individual layers.

A ratio of an area of the heater 134 to an area of the nozzle 130 may begreater than seven to one. In one embodiment, the heater 134 is square,with each side having a length 147. The length may be 47 microns, 51microns, or 71 microns. This would have an area of 2209, 2601, or 5041microns square, respectively. If the nozzle diameter is 20 microns, anarea at the second end would be 314 microns square, giving anapproximate ratio of 7 to 1, 8 to 1, or 16 to 1, respectively.

FIG. 8B is a cross-section view through the die along the cut line 8B-8Bin FIG. 6A. A length of the first contact 154 can be seen adjacent tothe inlet 94. A via 151 couples the first contact 154 to trace 155 thatis formed on the first dielectric layer 162. The second dielectric layer164 is on the trace 155. A via 149 is formed through the seconddielectric layer 164 and couples the trace 155 to the contact pad 152. Aportion of the ground line 158 is visible toward an edge 163 of the die,between the via 149 and the edge 163.

As can be seen in this cross-section, the die 92 is relatively simpleand does not include complex integrated circuitry. This die 92 will becontrolled and driven by an external microcontroller or microprocessor.The external microcontroller or microprocessor may be provided in thehousing. This allows the board 64 and the die 92 to be simplified andcost effective.

This die 92 is a thermal heating die that is free of complicated activecircuitry. In this embodiment, there are two metal or conductive levelsformed on the substrate. These conductive levels include the contact 154and the trace 155. In some embodiments, all of these features can beformed on a single metal level. This allows the die to be simple tomanufacture and minimizes the number of layers of dielectric between theheater and the chamber.

Referring now to FIG. 9, there is provided a close-up view of a portionof a microfluidic cartridge 26 illustrating a flow path with a filter 96between the second end 84 of the fluid transport member 80 and the die92 in accordance with one embodiment. The second through hole 78 of themicrofluidic delivery member 80 may include a liner 100 that coversexposed sidewalls 102 of the board 106. The liner 100 may be anymaterial configured to protect the board 106 from degradation due to thepresence of the fluid, such as to prevent fibers of the board fromseparating. In that regard, the liner 100 may protect against particlesfrom the board 106 entering into the fluid path and blocking the nozzles130. For instance, the second through hole 78 may be lined with amaterial that is less reactive to the fluid in the reservoir than thematerial of the board 106. In that regard, the board 106 may beprotected as the fluid passes therethrough. In one embodiment, thethrough hole is coated with a metal material, such as gold.

Upon depletion of the fluid in the reservoir 50, the microfluidiccartridge 26 may be removed from the housing 10 and replaced withanother microfluidic cartridge 26.

Operating System

The microfluidic delivery system 10 includes programmable electronicdrive circuitry to set a precise intensity level and delivery rate (inmilligrams per hour) of a fluid composition to provide a consumerbenefit, such as good room-fill in large living spaces with minimaldeposition and minimal clogging (e.g. wick clogging). In operation, themicrofluidic delivery system 10 may deliver a spray of micro droplets inwhich the majority of emitted droplets project at least about 4 cm toabout 12 cm, or about 8 cm to about 12 cm upward from the nozzles 130 toprovide noticeable delivery of the fluid composition to a space whileminimizing deposition.

The delivery system 10 may allow a user to adjust the intensity and/orthe timing of delivering the fluid composition for personal preference,efficacy, or for room size. For example, the delivery system 10 mayprovide ten intensity levels for a user to select and user selectedoptions of delivering the fluid composition every 6, 12, or 24 hours.

The microfluidic delivery system 10 can be run in one of two modes: (1)normal operation and (2) refill limited. In normal operation mode, thesystem is running at a frequency that enables the chambers 128 to refillto a degree substantially equal to their static sill volume such thatdroplet ejection is consistent in volume and shape. In contrast, refilllimited mode is an operating condition whereby the drive circuitry firesat a rate faster than the time required for the fluid to substantiallyrefill the chamber 128. By operating in the refill limited mode, thesystem 10 can force the drops that are ejected to have a smaller size,higher velocity, and random shape distribution which can lead to lessdeposition on the housing 12, microfluidic delivery member 64 orsurrounding surfaces. These drops are typically smaller than the nozzlediameter at higher burst frequency. With printing applications thisrandom shape and size can be problematic for high print resolution butit can be an advantage in the case of atomizing a liquid into the air.Operating in refill limited mode allows smaller droplets to be ejectedwhile avoiding complex micro fabrication processes to construct smallnozzle diameters, which may be more prone to clogging. The small dropletdistribution may have the advantage of evaporating faster compared to adroplet distribution produced under normal operating mode, possiblyminimizing surface deposition and far reaching in space due to diffusionkinetics.

The drive circuitry is powered by about 4 to about 24 Volts, or about 4to about 16 Volts from an external power source. The heating element 134is electrically connected to a microprocessor, which may be part of thedevice or cartridge and comprises software programmed to controloperation of the heating element 134 such as firing time, firingsequence, and frequency of the heating element. When the heating element134 is activated under the direction of the software, the fluidcomposition emits from the nozzles 130.

Referring to FIG. 10, the microprocessor supplies firing pulses having afire time (denoted t_(FIRE)) to a heating element 134. In someembodiments as shown in FIG. 10, a plurality of individual heatingelements are fired sequentially (1, 2, 3, 4, etc), with an interposeddelay time (denoted t_(DELAY)), in a sequence referred to as a burst.Bursts occur at a burst frequency (denoted f_(BURST)) of about 100 toabout 8000 Hertz, or about 100 to about 6000 Hertz, or about 1000 toabout 6000 Hertz, or about 1000 to about 5000 Hertz, or about 2000 to5000 Hertz or about 1000 to about 2500 Hertz, during a firing period(denoted t_(ON)). In an embodiment where heating elements 134 areconfigured to be fired sequentially, the burst frequency (f_(BURST)) isequivalent to the firing frequency of an individual nozzle.

It has been found that the firing frequency will impact droplet size aswell as how far upward the droplet is ejected which is important foravoiding deposition. With higher rates (e.g. 5000 Hertz), the dropletsare fired at 5000 times/second which provides more momentum for thefollowing droplets and hence causes the droplets to be ejected furtherwhich may help reduce deposition on surrounding surfaces. In addition,at 5000 Hertz the droplets are smaller for a given chamber size due toinsufficient time to completely fill the chamber which has been definedabove as refill limited mode.

The firing period (t_(ON)) may have a duration of about 0.25 seconds toabout 10 seconds, or about 0.5 seconds to about 2 seconds, or about 0.25seconds to about 1 second. A non-firing period (denoted t_(OFF))—whereno firing pulses are supplied to the heating element 134, may have aduration of about 9 seconds to about 200 seconds. When in a continuousrepeat mode the t_(ON) and t_(OFF) are repeated continuously over anextended period of time to deliver a desired mg/hr rate of fluid. Forexample, with a burst frequency of 5000 Hertz and a firing period(t_(ON)) of 0.5 seconds, each nozzle is firing 2500 times during thatsequence. If the t_(OFF) is 10 seconds, then the sequence will berepeated every 10.5 seconds or about 6 times/minute and the totalfirings of each nozzle would be 2500 multiplied by about 6 times/min orabout 15,000 firings/min. This delivery rate, per table 1, with 20nozzles firing will deliver about 90 mg/hour of fluid composition intothe air.

In another example of continuous repeat mode at 5000 Hz, to deliver 5mg/hr of fluid composition, the heating element 134 may have firingperiods (torr) and non-firing periods (t_(OFF)) comprising a 0.3% dutycycle (e.g. 0.5 second firing and 160 seconds non-firing). To deliver 57mg/hr, the heating element may have firing and non-firing periodscomprising a 2.4% duty cycle (e.g. 0.5 second firing and 20 secondsnon-firing). In the case of an electromechanical actuator as theactivation element, the stated heating element could be a piezo element.Table 1 and FIG. 10 show a firing pattern for the heating element 134 ofthe 1 to 2 microsecond pulse is repeated at the rates below to achieveintensity levels from level 1 to level 10 (or 5 to 90 mg/hr).

TABLE 1 Intensity mg/hour t_(FIRE) t_(DELAY) t_(ON) (s) t_(OFF) (s)f_(BURST) (Hz) 1 5 2 us 8 us .5 sec 160 sec 5000 2 10 2 us 8 us .5 sec100 sec 5000 3 15 2 us 8 us .5 sec 70 sec 5000 4 20 2 us 8 us .5 sec 50sec 5000 5 25 2 us 8 us .5 sec 40 sec 5000 6 31 2 us 8 us .5 sec 30 sec5000 7 43 2 us 8 us .5 sec 25 sec 5000 8 57 2 us 8 us .5 sec 20 sec 50009 72 2 us 8 us .5 sec 15 sec 5000 10 90 2 us 8 us .5 sec 10 sec 5000

In boost mode, the heating elements 134 may have a firing period (torr)of about 0.5 seconds and a non-firing period (t_(OFF)) of about 0.5seconds and repeated 20 times over approximately 20 seconds to deliverapproximately 5 mg of fluid composition into the air. This number ofrepeats for a one-time boost can be adjusted with software as desired.

The chamber 128 dimensions (e.g. inlet width, inlet thickness, surfacetension of the inlet flow paths as well as the liquid properties(surface tension and viscosity)) can all impact what is the desiredfrequency for either normal operation mode or refill limited mode. Witha recent example, the inventors have found that firing frequency of lessthan 2000 Hertz tends to result in normal operation mode where as whenthe electrical signal fires at frequencies of 4000 Hertz or higher, thesystem tends to be in a refill limited mode with significantly smallerdroplets relative to the nozzle diameter and more fine fragments. Whilerefill limited mode may be a problem for printing ink onto paper withcertain resolution, it is may be an advantage for systems designed tovolatilize a liquid into the air or depositing compositions onto asurface.

As part of the operation of the heating element 134, it is possible tosupply one or more preheating pulses with a preheating duration (denotedt_(HEAT)) which is always less than t_(FIRE) for the sole purpose ofpreheating the liquid in the chamber. The level and rate of preheatingis controlled by the number and duration of pulses supplied. Thepreheating of fluid could be important to lowering the viscosity of thesystem and hence making for more realizable firing of fluids. With lowerviscosity, exit velocities are also higher which improves throw distanceof the droplets.

As part of the operating conditions, under device ideal state, one canintroduce a “keep wet spitting” (“KWS”) operation for the sole purposeof maintaining nozzle health over time. KWS is firing operation at verylow frequency in order to balance the dry out phenomenon with wasteddelivered fluid. In the case of perfumes, a KWS of 0.1 to 0.0001 Hertzis sufficient to keep the nozzles healthy. Dry out is meant to be fluidcompositional changes over time that impact jetting performance (e.g.viscosity, low BP constitutes, etc)

In multiple reservoir delivery systems, a microprocessor and timer couldbe installed to emit the fluid composition from individual reservoirs atdifferent times and for selected time periods, including emitting thevolatile compositions in an alternating emission pattern as described inU.S. Pat. No. 7,223,361. Additionally, the delivery system could beprogrammable so a user can select certain compositions for emission. Inthe case of scented perfumes being emitted simultaneously, a customizedscent may be delivered to the air. It is also understood that in a multichamber system the drive circuitry (voltage, t_(FIRE), t_(HEAT), etc)could be different in the same device

While the heating element 134 for each chamber 128 is illustrated inFIG. 10 sequentially, the heating elements could be activatedsimultaneously, or in a pre-determined pattern/sequence (e.g. row 1:nozzles 1, 5, 10, 14, 18; etc. . . . ). In some embodiments, the heatingelements are pulsed in a staged manner since this may avoid coalescenceof adjacent droplets but also avoids high power draws that may drain abattery faster. Ideally, the heating elements 134 are pulsedsequentially and preferably in a sequence that skips nozzles such thatno two adjacent nozzles are ejecting fluid in sequence. In someembodiments, 20% of the heating elements 134 are fired simultaneouslyand then next 20% are fired, etc. In such an embodiment, it is preferredbut not necessary that no two adjacent nozzles eject fluidsimultaneously.

The nozzles 130 may be grouped together with other nozzles to form agroup in which each group may be spaced from each other by at least apredetermined minimum number of nozzles. And, each of the nozzles 130 ina group is spaced from the nozzles in the subsequently enabled group byat least the predetermined minimum number of nozzles.

In some embodiments, the operating system of the microfluidic deliverysystem 10 delivers from about 5 mg to about 90 mg, or about 5 mg toabout 40 mg, of fluid composition per hour into the air. Delivery rateof fluid composition can be calculated according to the following:Average droplet mass*number of nozzles*frequency*cumulative seconds of t_(ON)/hour (sec/hr)=5 to 90 mg/hr.For example, if t_(ON) is 0.5 sec and t_(OFF) is 59.5 seconds thencumulative torr time would be 30 second/hour. Further, if averagedroplet mass is 0.000004 mg and one is using 20 nozzles at 5000 Hertzfrequency the mg/hour with cumulative t_(ON) of 30 seconds=12 mg/hour.Optional FeaturesFan

In another aspect of the invention, the delivery system may comprise afan to assist in driving room-fill and to help avoid deposition oflarger droplets from landing on surrounding surfaces that could damagethe surface. The fan may be any known fan, such as a 5V 25×25×5 mm DCaxial fan (Series 250, Type255N from EBMPAPST), used in the art for airfreshening systems that delivers 1-1000 cubic centimeters of air/minute,alternatively 10-100 cubic centimeters/minute.

Sensors

In some embodiments, the delivery system may include commerciallyavailable sensors that respond to environmental stimuli such as light,noise, motion, and/or odor levels in the air. For example, the deliverysystem can be programmed to turn on when it senses light, and/or to turnoff when it senses no light. In another example, the delivery system canturn on when the sensor senses a person moving into the vicinity of thesensor. Sensors may also be used to monitor the odor levels in the air.The odor sensor can be used to turn-on the delivery system, increase theheat or fan speed, and/or step-up the delivery of the fluid compositionfrom the delivery system when it is needed.

In some embodiments, a VOC sensors can be used to measure intensity ofperfume from adjacent or remote devices and alter the operationalconditions to work synergistically with other perfume devices. Forexample a remote sensor could detect distance from the emitting deviceas well as fragrance intensity and then provide feedback to device onwhere to locate device to maximize room fill and/or provide the“desired” intensity in the room for the user.

In some embodiments, the devices can communicate with each other andcoordinate operations in order to work synergistically with otherperfume devices.

The sensor may also be used to measure fluid levels in the reservoir orcount firing of the heating elements to indicate the cartridge'send-of-life in advance of depletion. In such case, an LED light may turnon to indicate the reservoir needs to be filled or replaced with a newreservoir.

The sensors may be integral with the delivery system housing or in aremote location (i.e. physically separated from the delivery systemhousing) such as remote computer or mobile smart device/phone. Thesensors may communicate with the delivery system remotely via low energyblue tooth, 6 low pan radios or any other means of wirelesslycommunicating with a device and/or a controller (e.g. smart phone orcomputer).

In another embodiment, the user can change the operational condition ofthe device remotely via low energy blue tooth, or other means.

Smart Chip

In another aspect of this invention, the cartridge has a memory in orderto transmit optimal operational condition to the device. We expectoperational optimal condition for be fluid dependent in some cases.

The delivery system may be configured to be compact and easily portable.In such case, the delivery system may be battery operated. The deliverysystem may be capable for use with electrical sources as 9-voltbatteries, conventional dry cells such as “A”, “AA”, “AAA”, “C”, and “D”cells, button cells, watch batteries, solar cells, as well asrechargeable batteries with recharging base.

Fluid Composition

To operate satisfactorily in a microfluidic delivery system, manycharacteristics of a fluid composition are taken into consideration.Some factors include formulating fluids with viscosities that areoptimal to emit from the microfluidic delivery member, formulatingfluids with limited amounts or no suspended solids that would clog themicrofluidic delivery member, formulating fluids to be sufficientlystable to not dry and clog the microfluidic delivery member, etc.Operating satisfactorily in a microfluidic delivery system, however,addresses only some of the requirements necessary for a fluidcomposition having more than 50 wt. % of a perfume mixture to atomizeproperly from a microfluidic delivery member and to be deliveredeffectively as an air freshening or malodor reducing composition.

The fluid composition of the present invention may exhibit a viscosityof less than 20 centipoise (“cps”), alternatively less than 18 cps,alternatively less than 16 cps, alternatively from about 5 cps to about16 cps, alternatively about 8 cps to about 15 cps. And, the volatilecomposition may have surface tensions below about 35, alternatively fromabout 20 to about 30 dynes per centimeter. Viscosity is in cps, asdetermined using the Bohlin CVO Rheometer system in conjunction with ahigh sensitivity double gap geometry.

In some embodiments, the fluid composition is free of suspended solidsor solid particles existing in a mixture wherein particulate matter isdispersed within a liquid matrix. Free of suspended solids isdistinguishable from dissolved solids that are characteristic of someperfume materials.

In some embodiments, the fluid composition of the present invention maycomprise volatile materials. Exemplary volatile materials includeperfume materials, volatile dyes, materials that function asinsecticides, essential oils or materials that acts to condition,modify, or otherwise modify the environment (e.g. to assist with sleep,wake, respiratory health, and like conditions), deodorants or malodorcontrol compositions (e.g. odor neutralizing materials such as reactivealdehydes (as disclosed in U.S. 2005/0124512), odor blocking materials,odor masking materials, or sensory modifying materials such as ionones(also disclosed in U.S. 2005/0124512)).

The volatile materials may be present in an amount greater than about50%, alternatively greater than about 60%, alternatively greater thanabout 70%, alternatively greater than about 75%, alternatively greaterthan about 80%, alternatively from about 50% to about 100%,alternatively from about 60% to about 100%, alternatively from about 70%to about 100%, alternatively from about 80% to about 100%, alternativelyfrom about 90% to about 100%, by weight of the fluid composition.

The fluid composition may contain one or more volatile materialsselected by the material's boiling point (“B.P.”). The B.P. referred toherein is measured under normal standard pressure of 760 mm Hg. The B.P.of many perfume ingredients, at standard 760 mm Hg can be found in“Perfume and Flavor Chemicals (Aroma Chemicals),” written and publishedby Steffen Arctander, 1969.

In the present invention, the fluid composition may have an average B.P.of less than 250° C., alternatively less than 225° C., alternativelyless than 200° C., alternatively less than about 150° C., alternativelyless than about 120° C., alternatively less than about 100° C.,alternatively about 50° C. to about 200° C., alternatively about 110° C.to about 140° C. In some embodiments a quantity of low B.P. ingredients(<200 C) can be used to help higher B.P. formulations to be ejected. Inone example, a formula with BP above 25° could be made to eject withgood performance if 10-50% of the formula's ingredients has a B.P. lessthan 200 C despite the overall average still being above 250° C.

In some embodiments, the fluid composition may comprise, consistessentially of, or consist of volatile perfume materials.

Tables 2 and 3 outline technical data on perfume materials suitable forthe present invention. In one embodiment, approximately 10%, by weightof the composition, is ethanol which may be used as a diluents to reduceboiling point to a level less than 250° C. Flash point may be consideredin choosing the perfume formulation as flash points less than 70° C.require special shipping and handling in some countries due toflammability. Hence, there may be advantages to formulate to higherflash points.

Table 2 lists some non-limiting, exemplary individual perfume materialssuitable for the fluid composition of the present invention.

TABLE 2 CAS Number Perfume Raw Material Name B.P.(° C.) 105-37-3 Ethylpropionate 99 110-19-0 Isobutyl acetate 116 928-96-1 Beta gamma hexenol157 80-56-8 Alpha Pinene 157 127-91-3 Beta Pinene 166 1708-82-3cis-hexenyl acetate 169 124-13-0 Octanal 170 470-82-6 Eucalyptol 175141-78-6 Ethyl acetate 77

Table 3 shows an exemplary perfume mixture having a total B.P. less than200° C.

TABLE 3 CAS Number Perfume Raw Material Name Wt % B.P.(° C.) 123-68-2Allyl Caproate 2.50 185 140-11-4 Benzyl Acetate 3.00 214 928-96-1 BetaGamma Hexenol 9.00 157 18479-58-8 Dihydro Myrcenol 5.00 198 39255-32-8Ethyl 2 Methyl Pentanoate 9.00 157 77-83-8 Ethyl Methyl Phenyl Glycidate2.00 260 7452-79-1 Ethyl-2-Methyl Butyrate 8.00 132 142-92-7 HexylAcetate 12.50 146 68514-75-0 Orange Phase Oil 25Xl.18%-Low 10.00 177Cit. 14638 93-58-3 Methyl Benzoate 0.50 200 104-93-8 Para Cresyl MethylEther 0.20 176 1191-16-8 Prenyl Acetate 8.00 145 88-41-5 Verdox 3.00 22358430-94-7 Iso Nonyl Acetate 27.30 225 TOTAL: 100.00

When formulating fluid compositions for the present invention, one mayalso include solvents, diluents, extenders, fixatives, thickeners, orthe like. Non-limiting examples of these materials are ethyl alcohol,carbitol, diethylene glycol, dipropylene glycol, diethyl phthalate,triethyl citrate, isopropyl myristate, ethyl cellulose, and benzylbenzoate.

In some embodiments, the fluid composition may contain functionalperfume components (“FPCs”). FPCs are a class of perfume raw materialswith evaporation properties that are similar to traditional organicsolvents or volatile organic compounds (“VOCs”). “VOCs”, as used herein,means volatile organic compounds that have a vapor pressure of greaterthan 0.2 mm Hg measured at 20° C. and aid in perfume evaporation.Exemplary VOCs include the following organic solvents: dipropyleneglycol methyl ether (“DPM”), 3-methoxy-3-methyl-1-butanol (“MMB”),volatile silicone oil, and dipropylene glycol esters of methyl, ethyl,propyl, butyl, ethylene glycol methyl ether, ethylene glycol ethylether, diethylene glycol methyl ether, diethylene glycol ethyl ether, orany VOC under the tradename of Dowanol™ glycol ether. VOCs are commonlyused at levels greater than 20% in a fluid composition to aid in perfumeevaporation.

The FPCs of the present invention aid in the evaporation of perfumematerials and may provide a hedonic, fragrance benefit. FPCs may be usedin relatively large concentrations without negatively impacting perfumecharacter of the overall composition. As such, in some embodiments, thefluid composition of the present invention may be substantially free ofVOCs, meaning it has no more than 18%, alternatively no more than 6%,alternatively no more than 5%, alternatively no more than 1%,alternatively no more than 0.5%, by weight of the composition, of VOCs.The volatile composition, in some embodiments, may be free of VOCs.

Perfume materials that are suitable as FPCs are disclosed in U.S. Pat.No. 8,338,346.

Throughout this specification, components referred to in the singularare to be understood as referring to both a single or plural of suchcomponent.

All percentages stated herein are by weight unless otherwise specified.

Every numerical range given throughout this specification will includeevery narrower numerical range that falls within such broader numericalrange, as if such narrower numerical range were all expressly writtenherein. For example, a stated range of “1 to 10” should be considered toinclude any and all subranges between (and inclusive of) the minimumvalue of 1 and the maximum value of 10; that is, all subranges beginningwith a minimum value of 1 or more and ending with a maximum value of 10or less, e.g., 1 to 6.1, 3.5 to 7.8, 5.5 to 10, etc.

Further, the dimensions and values disclosed herein are not to beunderstood as being strictly limited to the exact numerical valuesrecited. Instead, unless otherwise specified, each such dimension isintended to mean both the recited value and a functionally equivalentrange surrounding that value. For example, a dimension disclosed as “40mm” is intended to mean “about 40 mm.”

Every document cited herein, including any cross referenced or relatedpatent or application, is hereby incorporated herein by reference in itsentirety unless expressly excluded or otherwise limited. The citation ofany document is not an admission that it is prior art with respect toany invention disclosed or claimed herein or that it alone, or in anycombination with any other reference or references, teaches, suggests ordiscloses any such invention. Further, to the extent that any meaning ordefinition of a term in this document conflicts with any meaning ordefinition of the same term in a document incorporated by reference, themeaning or definition assigned to that term in this document shallgovern.

While particular embodiments of the present invention have beendescribed, it would be obvious to those skilled in the art that variousother changes and modifications can be made without departing from thespirit and scope of the invention. It is therefore intended to cover inthe appended claims all such changes and modifications that are withinthe scope of this invention.

The invention claimed is:
 1. A microfluidic delivery system comprising:a reservoir; a transport member disposed in the reservoir and comprisinga capillary tube or a wicking material; and a microfluidic diecomprising a silicon substrate, a conductive layer, and a polymer layer,the silicon substrate comprising a channel for delivering a fluidcomposition, the fluid composition comprising a perfume mixture, to thepolymer layer, the polymer layer comprising a plurality of nozzles fordispensing the fluid composition and at least one chamber in fluidcommunication with at least one of the plurality of nozzles, whereineach nozzle comprises a lower opening proximal to the chamber and anupper opening distal to the chamber, and the conductive layer comprisingelectrical traces and at least one heating element that heats the fluidcomposition in the chamber by receiving an electrical firing pulse,wherein the ratio of the area of the heating element to the area of theupper opening of the nozzle is 5:1 or greater, and wherein theelectrical firing pulse is delivered during a firing period (tON) from0.25 seconds to 10 seconds and wherein the firing period (tON) isfollowed by a non-firing period (tOFF) having a duration of 9 seconds to200 seconds, and wherein, during the firing period, the electricalfiring pulse is pulsed at 100 Hertz to 8000 Hertz.
 2. The microfluidicdelivery system of claim 1, wherein the microfluidic die furthercomprises a separate heating element for each of the plurality ofnozzles.
 3. The microfluidic delivery system of claim 2, wherein themicrofluidic die comprises 8 to 64 heating elements.
 4. The microfluidicdelivery system of claim 2, wherein the upper opening of each nozzle is10 to 50 micrometers.
 5. The microfluidic delivery system of claim 2,wherein the microfluidic die comprise a plurality of nozzles, thenozzles each having chamber volume of 5 to 15 picoliters.
 6. Themicrofluidic delivery system of claim 1, wherein each of the heatingelements comprises an area of 2500 microns square.
 7. The microfluidicdelivery system of claim 1, wherein the microfluidic die is controlledby a microprocessor, wherein the microprocessor is programmed to providea sequential firing signal to the heating element.
 8. The microfluidicdelivery system of claim 1, further providing 4 to 16 volts of energy tothe heating element.
 9. The microfluidic delivery system of claim 1,wherein the microfluidic delivery member delivers from 5 mg to 90 mg ofa fluid composition per hour into the air.
 10. The microfluidic deliverysystem of claim 1, wherein the microfluidic die emits 1 to 10 picolitersof a volatile composition into the air from each of the plurality ofnozzles per electrical firing pulse.
 11. The microfluidic deliverysystem of claim 1 further comprising a sensor selected from the groupconsisting of a motion sensor, wireless sensor beacon, a light sensor, afluid detection sensor, an odor detection sensor, and combinationsthereof.
 12. The microfluidic delivery system of claim 1, furthercomprising a reservoir comprising the perfume mixture, the perfumemixture having a boiling point less than 250° C.
 13. The microfluidicdelivery system of claim 12, wherein the boiling point is less than 200°C.
 14. The microfluidic delivery system of claim 12 wherein 5% to 50%,by weight of the perfume mixture, comprise individual perfume materialshaving a boiling point less than 200° C.
 15. The microfluidic deliverysystem of claim 12, wherein the perfume mixture further comprises afunctional perfume component present in an amount of 50% to 100%, byweight of the perfume mixture wherein the functional perfume componentis selected from the group consisting of: iso-nonyl acetate, dihydromyrcenol (3-methylene-7-methyl octan-7-ol), linalool (3-hydroxy-3,7-dimethyl-1, 6 octadiene), geraniol (3, 7 dimethyl-2, 6-octadien-1-ol),d-limonene (1-methyl-4-isopropenyl-1-cyclohexene, benzyl acetate,isopropyl myristate, and mixtures thereof.
 16. The microfluidic deliverysystem of claim 1, wherein the microfluidic die comprises a separatechamber for each of the plurality of nozzles.
 17. The microfluidicdelivery system of claim 1, wherein, during the firing period, theelectrical firing pulse is pulsed at 500 Hertz to 8000 Hertz.